Video display controllers such as a VGA display controller include at least one digital-to-analog converter (DAC) to form one or more analog video signals for display on an analog display monitor. Such a signal typically has the form of steps (treads) that are typically smoothed by a reconstruction filter. It is desired to convert such one or more analog signals to digital form, e.g., in a terminal of a videoconferencing system for compression and transmission to one or more other terminals at remote locations. Such resampling is carried out at sampling points that are ideally positioned at the center of each tread of the DAC output(s) in order to avoid blurring and/or other undesired effects.
The video image from the video display controller may be a static image typical of a desktop on a computer display. Such an image may include one or more windows in which motion video is being displayed.